Dumbbells have long been used for exercise purposes. In general, dumbbells have been designed for use in arm, shoulder and chest development exercises in which they are raised and lowered by the user. Typical of such dumbbells are the conventional pair of generally cylindrical weights on opposite ends of a hand grip.
Fixed dumbbells have been proposed which have a flat base and which allow push ups to be performed by the user grasping a dumbbell in each hand and resting their bases upon the ground to support his weight. However, despite the flat base, slips can occur when these prior art devices are used to perform push ups in this manner as the rigid weights lack stability when supported on uneven surfaces. These flat-based dumbbells are also well suited to exercises such as bench presses, inclines and shoulder work which typically begin and end with the dumbbells resting on the knees of the user as they are less unwieldy and painful to support in this manner, compared to conventional dumbbells.
Moreover flat-based dumbbells can be used for other exercises for which conventional symmetrical dumbbells are unsuited. These exercises include, for instance, wrist exercises where the device is grasped and held such that the centre of gravity is offset from the handle to apply a torque to the wrist. It will be understood that, due to the symmetrical distribution of weight relative to the handle in conventional dumbbells, this type of exercise cannot be performed. However, the maximum torque that can be applied during wrist exercises as described, is limited in one direction by the prior art device striking the user's wrist or forearm. Furthermore these fixed dumbbells are compact, but are typically sold in sets stored on a rack that is bulky and cumbersome.
Adjustable dumbbells are space and cost efficient exercise equipment, however, adjustable dumbbells also suffer from some drawbacks. Conventionally adjustable dumbbells have incorporated plates and locking collars secured to the ends of an extended handle but it can be time-consuming removing and replacing the locking collars and plates to change or adjust both dumbbells. It is an object of the present invention to overcome or substantially ameliorate the above disadvantages or more generally to provide an improved exercise device.